1. Field of the Invention
The present invention relates to novel additive compositions for use in lubricating oils. More particularly, the invention is directed to multi-purpose additives, lubricants and concentrates containing the same. By multi-purpose additive is meant an additive which provides a lubricant with at least two functional properties such as dispersancy and improvement in viscosity index.
2. Description of the Prior Art
Prior art additives functioning as viscosity index (VI) improvers and dispersants have comprised a variety of nitrogen-containing or oxygen-containing polymeric substances and adducts. Generally, the functionality believed responsible for VI improvement is derived from the polymeric nature of the additive as exemplified by its molecular weight (usually high) and morphology (usually amorphous). Collaterally, dispersancy/detergency aspects have been attributed to the additive's nitrogen and sometimes oxygen-containing moieties. Accordingly, it has been a typical approach to inter-react a known viscosity index improver with a known detergent/dispersant. Often, the resulting product either lacked in both functionalities or had one inferior functionality. The reason for this is that it is difficult to prepare such additives without sacrificing some important inherent aspects. Typical prior art additives include reaction products of ethyene-propylene copolymer with maleic anhydride and polyamine, ethylene-propylene-non-conjugated diene terpolymer with maleic anhydride and polyamine, and ethylene-propylene-1,4-hexadiene terpolymer with maleic anhydride and polyol. For review of prior art disclosures concerning multi-purpose additives and particularly as related to VI improvers and/or dispersants reference is made to the following prior art U.S. Pat. Nos. whose disclosures are incorporated herein by reference; 2,973,344, 3,488,049, 3,799,877, 3,278,550, 3,513,095, 3,842,010, 3,311,558, 3,563,960, 3,864,098, 3,312,619, 3,598,738, 3,864,268, 3,326,804, 3,615,288, 3,879,304, 3,403,011, 3,637,610, 4,033,889, 3,404,091, 3,652,239, 4,051,048, 3,445,389, 3,687,849. The significance of a multi-purpose additive cannot be overestimated, particularly in terms of the economical advantages gained by employing a single additive in place of two or more additives.
It is therefore a primary object of this invention to provide novel multi-purpose lubricant additives.
A more specific object of the invention is to provide multi-purpose additives directed to improving lubricants' viscosity index and their dispersancy/detergency properties.
A further object is to provide processes for preparing such multi-purpose additives, as well as lubricants and concentrates containing the same.
Other objects and advantages will become more apparent from the following description.